Note: Descriptions are shown in the official language in which they were submitted.
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High Pressure Pasteurizing of Frozen Ground Meats
FIELD
[0001 ] The present invention relates to preservation of frozen ground meats.
In particular, the
present invention relates to preservation of frozen ground meat by application
of high pressure.
BACKGROUND OF THE INVENTION
[0002] Ground meat products are distributed either fresh or frozen. The
advantage of using
frozen meat products is a significantly longer shelf life compared to fresh
meat products
(typically 120-365 days versus 25 days or less). Therefore inventory risk
(shortages and being
long on inventory) is a lesser concern of fresh distribution.
[0003] A risk associated with frozen ground meats is the potential
contamination by pathogens
such as E. coli or Salmonella.
[0004] According to US Patent No. 6,033,701, the use of pressure for
sterilization of food was
discovered early in the 20th century. Early reports of the use of pressure in
sterilization focused
on fruits. High pressure has been used for treatment of certain foods, such as
fish meat and/or
kneaded fish meat products as discussed in U.S. Patent No. 6,440,484 or raw
food products,
such as raw shellfish as described in U.S. Patent No. 6,537,601.
[0005] US Patent Nos. 5,593,714 and 6,033,701 describe food product treatment
processes
where the food product is treated at a pressure of 25,000 psi and a
temperature of 18-23 degrees
C for a time period of at least 5 days, or to at least 70 MPa pressure so that
said foodstuff or said
feedstuff is place under said pressure, maintaining said pressure on said
container and said
foodstuff or said feedstuff for more than 12 hours at a temperature of between
18 and 23 degrees
C, respectively. The very long retention time of these products under pressure
as required in
these patents is undesirable for mass production purposes.
[0006] Companies such as the American Pasteurization Company and Avure
Technologies use
or provide equipment to carry out High Pressure Processing (HPP) or both.
These companies
are careful to note that they are not food companies, but are equipment
suppliers to food
producers. Avure Technologies has been granted a number of patents, all
focusing on the
equipment and the processes for use of the equipment. The American
Pasteurization Company
currently lists foods that can be processed using HPP as:
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- Ready-to-eat meat products
- Soups & stews
- Various fruits & vegetables
- Oysters and shellfish
- Jams & jellies
- Sauces & dips
- Cheeses
http://www.amerpastco.com/faq.html
[0007] Clearly, HPP is not universally useful for treatment of food products,
and process
parameters have been developed that are product specific.
[0008] In 2001, the US FDA Center for Food Safety and Applied Nutrition
published an
Evaluation and Definition of Potentially Hazardous Foods that among other
strategies discussed
the use of HPP for Microbial Inactivation. The report stated:
[0009] Ground beef can be pasteurized by HPP to eliminate E. coli 0157:H7,
Listeria spp., Salmonella spp., or Staphylococcus spp. Much more work is
required to develop a suggested hold time at 580 MPa due to the potential for
tailing. Changes in product color and appearance may limit the usefulness of
HPP
treatment pressures above 200 to 300 MPa.
http://www.cfsan.fda.gov/-comm/ift4-5.html
[00010] Further study of use of HPP in inactivation of various microflora in
inoculated
ground beef has been carried out since the FDA report. For example, an article
entitled "High
Pressure Inactivation of Citrobacterfreundii, Pseudomonasfluorescens and
Listeria innocua in
Inoculated Minced Beef Muscle" by A. Carlez et al.; Lebensm.-Wiss.u.-
Technol., 26, pp. 357-
363 (1993) describes pressure treatment of minced beef under a range of
pressures for 20 minute
periods at various temperatures. This article notes that the greatest
reduction in microorganisms
was observed at 50 C. Similarly, an article entitled "High-pressure
destruction kinetics of
Clostridium sporogenes spores in ground beef at elevated temperatures" by
Songming Zhu et
al.; International Journal of Food Microbiology, 126 (2008) pp. 86-92,
combined high pressure
treatment with heat, 80-100 C, to provide effective destruction of spores.
[00011] The preservation of vegetables in contact with a noble gas, a mixture
of noble
gases or a mixture containing at least one noble gas is described in US Patent
No. 6,342,261.
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SUMMARY OF THE INVENTION
[00012] In the present process, frozen ground meat is packaged in a sealed
package. In an
embodiment of the invention, fresh ground meat is frozen and then packaged in
a sealed
package. In another embodiment, fresh ground meat is packaged in a sealed
package and then
frozen. This package of frozen ground meat is placed in a pressurization
vessel, which is
pressurized to at least about 50,000 psi pressure, so the packaged frozen
ground meat is placed
under elevated pressure. This elevated pressure is maintained for a time of
from about 1 to
about 300 seconds. Preferably, the packaged frozen ground meat is at a
temperature of from
about -50 to about 45 F during the pressurization process. The pressure on
the packaged frozen
ground meat is then reduced to ambient pressure and the packaged frozen ground
meat is
removed from the pressurization vessel.
[00013] The present invention provides an advantage in preservation of ground
meat
products by efficiently killing or otherwise deactivating or rendering
harmless pathogens in the
meat and decreasing the risk of pathogen contamination of food eaten by the
consumer. In
another aspect, spoilage organisms often introduce off odors and flavors in
meat even before the
meat is unhealthy for consumption. The present invention can improve the
length of time that a
meat product is at high quality as compared to prior art processes. By use of
high pressure,
ground meat can advantageously be treated without the use of chemical
treatments or
incorporation of preservatives that some consumers may find objectionable. In
an embodiment
of the present invention, ground meat products can be prepared using less than
half of the
amount of preservatives (such as lactates or salt) as compared to like ground
meat products that
have not been processed using pressure as described herein. In an embodiment
of the present
invention, the frozen ground meat additionally contains non-endogenous
antimicrobial treatment
chemicals to further decrease the risk of pathogen contamination of food eaten
by the consumer.
In an embodiment of the present invention, the frozen ground meat is free of
non-endogenous
antimicrobial treatment chemicals. In another embodiment of the present
invention, the frozen
ground meat is free of stabilizers, preservatives and similar processing aids.
[00014] Surprisingly, the pressure used in the present process under the
conditions of
treatment has been found to be effective in killing pathogens in the meat in a
very short period
of time, enabling this process to be used in production scale settings.
Because the pathogen
killing step can be carried out in a time of less than about 300 seconds,
preferably less than
about 150 seconds, and more preferably less than about 90 seconds, large scale
production
facilities can use the present process without undue delay in production. This
is advantageous
because meat producers can immediately respond to product shortages by quickly
providing
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healthy ground meat product that has been treated for pathogens without time-
consuming
product treatment steps.
[00015] Additionally, the present process is surprisingly effective even
though the meat is
frozen. Thus, pathogens can be effectively killed in ground meat while at the
same time
maintaining preferred processing conditions whereby the ground meat never
exceeds the
temperature of 45 F. This allows meat producers to establish an HACCP program
using well
recognized safe temperature handling protocols without the need to heat the
meat. The present
invention thus provides a process whereby meat can be processed without
transitioning the meat
through undesirable temperature ranges (i.e. above conventional refrigeration
temperatures and
below cooking temperatures).
[00016] It has surprisingly been found that frozen ground meat processed in
the manner of
the present invention can exhibit a significant reduction in pathogen risk by
reducing E. coli
0157:H7 by at least 4 log and preferably 5 log.
[00017] The above advantages as recognized in the treatment of frozen ground
meat are
similarly apparent in the treatment of fresh ground meat.
DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS
[00018] The embodiments of the present invention described below are not
intended to be
exhaustive or to limit the invention to the precise forms disclosed in the
following detailed
description. Rather a purpose of the embodiments chosen and described is so
that the
appreciation and understanding by others skilled in the art of the principles
and practices of the
present invention can be facilitated.
[00019] The meat to be treated in accordance with the present invention may be
any
variety of meat from any species. Suitable meats include those obtained from
bovine, porcine,
equine, caprine, ovine, avian animals, or any animal commonly slaughtered for
food production.
Bovine animals may include, but are not limited to, buffalo, and all cattle,
including steers,
heifers, cows, and bulls. Porcine animals may include, but are not limited to,
feeder pigs and
breeding pigs, including sows, gilts, barrows, and boars. Ovine animals may
include, but are not
limited to, sheep, including ewes, rams, wethers, and lambs. Poultry may
include, but are not
limited to, chicken, turkey, and ostrich. Preferably the meat is bovine meat,
and most preferably
beef.
[00020] The meat is ground in a conventional manner. In most large scale
processing
systems, the meat is first ground to V2 inch diameter portions, and the fat
content of the meat is
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adjusted to meet product requirements. The meat then typically is ground again
to provide 1/8
to 3/32 "noodles."
[00021] For purposes of discussion, the following description will focus on
the exemplary
embodiment wherein the meat to be treated is frozen. Distinct process and
storage benefits can
be in this embodiment. The ability to provide ground meat that has a reduced
amount of, or that
is free of, non-endogenous antimicrobial treatment chemicals is a distinct
advantage in the
frozen ground meat product. Similarly, the ability to provide frozen ground
meat that has a
reduced amount of, or that is free of stabilizers, preservatives and similar
processing aids is a
distinct advantage.
[00022] In an embodiment of the present invention, the frozen ground meat
contains
additional food inclusions. For example, the food inclusions may be selected
from mushrooms,
onions, garlic, cheeses and combinations thereof. In another embodiment, the
ground meat
contains seasoning inclusions. This is particularly advantageous because such
a combination
product provides consumers with the convenience they demand. Further, it is
exceptionally
difficult to provide combination products on a large commercial scale because
spoilage is
accelerated when such products are stored in combination.
[00023] The ground meat may be frozen either before or after packaging. If the
meat is
frozen after packaging, the meat is divided into appropriate portions and
packaged in a sealed
package. In an embodiment of the invention, the packaged frozen ground meat is
in a meat
portion (i.e. total amount of meat in the package) of from about 1/8 to about
25 pounds of meat,
and in another embodiment in a meat portion of from about 1/8 to about 5
pounds of meat.
Thus, the meat may be sized for use by institutional customers (e.g.
restaurant, food service, or
commercial users) or for the home consumer. The meat may be provided in any
format, such as
in the form of patties, pre-formed meat loaves, stuffed food products such as
stuffed peppers,
and the like. The packaged meat product is then frozen using commonly accepted
methods,
such as a mechanical freezing tunnel, conventional blast freezer, liquid
immersion, a nitrogen
tunnel, or other traditional freezing methods.
[00024] The package is an air-tight package suitable for storage, transport
and
presentation to the consumer. The packaging may be of a bulk, shipping, or
individual serving
type; wherein the container is a formable pouch, injectable pouch, sealable
pouch, formable tray,
vacuum formable tray or pouch, heat formable tray or pouch, or film covered
tray. In an
embodiment, the sealed package comprises a tray and has headspace over the
fresh ground meat.
Preferably, the frozen ground meat is packaged in a sealed package having an
oxygen displaced
gas environment, meaning that the amount of oxygen is at least less than
present in the common
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atmosphere, and preferably substantially less than is present in the common
atmosphere.
Reduction in the exposure of the ground meat to oxygen is advantageous,
because this reduces
oxidation of the meat. Preferably the gas environment within the meat
packaging is purged of
oxygen. In an embodiment, the gas environment comprises a gas selected from
carbon dioxide,
nitrogen, carbon monoxide, nitrous oxide, hydrogen, neon, argon, krypton,
xenon and mixtures
thereof.
[00025] In another embodiment, the meat is divided into appropriate portions
and then
frozen. The same methods may be used to freeze the packaged ground meat
product. For
example, ground meat patties may be frozen using a mechanical freezing tunnel.
In that case,
the patty is typically exposed to high velocity fans which circulate
refrigerated air at, for
example, -40 F, for a period of time, for example, three to seven minutes.
[00026] Ground meat is preferably subjected to a gaseous atmosphere as
discussed above
by flushing, injecting, sparging, applying a vacuum and then flushing,
pressurizing, or
introducing said gaseous atmosphere into an impermeable or semipermeable film
covering the
ground meat.
[00027] The packaged frozen ground meat may then be placed in a pressurization
vessel
and pressure may be applied in any appropriate manner. Equipment used to treat
materials using
high pressure is described, for example, in U.S. Patent Nos. 7,220,381;
5,316,745; 5,370,043;
7,310,990; and 7,096,774.
[00028] A preferred process comprises submerging the packaged frozen ground
meat in a
liquid within an enclosed vessel. Pressure is then generated either by pumping
more liquid into
the pressure vessel or by reducing the volume of the pressure chamber. This
pressure is
uniformly distributed over all materials in the vessel, and even packages with
headspace do not
ordinarily burst. The pressurization vessel containing the packaged frozen
ground meat is
pressurized to an elevated pressure of at least about 50,000 psi. Preferably,
the elevated pressure
is from about 50,000 psi to about 130,500 psi, more preferably from about
60,000 psi to about
115,000 psi, and even more preferably from about 85,000 psi to about 100,000
psi. The
packaged ground meat is treated under elevated pressure for a time of from
about 1 to about 300
seconds, more preferably for a time of from about 30 to about 150 seconds, and
even more
preferably for a time of from about 45 to about 70 seconds.
[00029] The pressurization is carried out at a temperature of from about -50 F
to about
45 F when the ground meat is frozen. Preferably, the temperature of the fresh
ground meat is
never above 30 F, and more preferably never above about 20 F during the entire
production
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process from the grinding step through to removal of the ground meat from the
pressurization
vessel.
[00030] Because the frozen ground meat product is already in a sealed package
before
treatment, the meat is not touched again or exposed to the air or any
potentially unsanitary
conditions until the package is opened by the consumer.
[00031] In a preferred embodiment of the present invention, the packaged
frozen ground
meat is submerged in liquid during the pressure treatment step. If the
packaging is faulty, the
present pressure treatment advantageously exposes any packaging defects such
as pinholes,
usually by permitting a detectable amount of liquid to enter into the package.
Thus the present
invention beneficially operates to reveal defective packaging that would lead
to premature
product spoilage if not detected.
[00032] In use, the packaged frozen ground meat is sold in distribution
channels in the
packages in which the meat was treated, ready for customer purchase. This
provides significant
advantages, in that the package remains sealed until the ultimate customer
(e.g. restaurant, food
service or home consumer) opens the package and uses the ground meat for the
desired purpose.
[00033] All patents, patent applications (including provisional applications),
and
publications cited herein are fully incorporated by reference herein for all
purposes as if
individually incorporated. Unless otherwise indicated, all parts and
percentages are by weight
and all molecular weights are weight average molecular weights. The foregoing
detailed
description has been given for clarity of understanding only. No unnecessary
limitations are to
be understood therefrom. The invention is not limited to the exact details
shown and described,
for variations obvious to one skilled in the art will be included within the
invention defined by
the claims.
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